You are likely thinking of the [Minnesota Starvation Experiment (1944–1945)](https://www.google.com/search?q=Minnesota+Starvation+Experiment+%281944%E2%80%931945%29&kgmid=/m/02qrcls), led by Dr. Ancel Keys. While it was technically a study on semi-starvation, the specific food the men were given to survive consisted almost entirely of carbohydrates and sugars, and several of the subjects famously suffered severe mental breakdowns ("went crazy"). [1, 2, 3] 
## The Details of the Experiment

* The Diet: To simulate what starving Europeans were eating during World War II, 36 healthy men were put on a grueling 6-month restriction. Their meals were strictly limited to carbohydrate-heavy foods: potatoes, root vegetables, bread, macaroni, and turnips. They were given almost no fat or meat. [2, 3, 4] 
* The Cognitive & Psychological Collapse: Because their brains and bodies were severely deprived of fats, proteins, and essential nutrients while running purely on a calorie-deficient carbohydrate deficit, the men suffered extreme psychological deterioration. [2, 3] 

## The Patients Who "Went Crazy"
The psychological effects were so severe that the experiment's psychiatric logs became legendary in nutrition science: [1] 

* The Obsession: The men became completely obsessed with food. They would stay up all night reading cookbooks, stare at pictures of food, and hoard utensils. [1, 2] 
* Self-Harm: One subject, 24-year-old Sam Legg, became so mentally unhinged and distressed by the carbohydrate starvation that he intentionally chopped off three of his own fingers with an axe while doing chore work. [3] 
* Psychosis and Violence: Another subject, unhinged by the diet, began having severe psychiatric breakdowns, experiencing vivid hallucinations, and threatening to murder Dr. Ancel Keys, forcing the staff to commit him to a psychiatric ward.

When the men were finally allowed to eat normally again during the refeeding phase, many experienced extreme binge-eating episodes, eating up to 10,000 calories a day because their brains' reward centers had been completely broken by the trial. [1, 2] 
Is the Minnesota Starvation Study the specific experiment you were trying to find, or were you thinking of a different historical trial involving isolated sugar/carb testing?

[1] [https://psychiatry.duke.edu](https://psychiatry.duke.edu/blog/starvation-experiment)
[2] [https://equip.health](https://equip.health/articles/understanding-eds/minnesota-starvation-experiment-restriction)
[3] [https://www.madinamerica.com](https://www.madinamerica.com/2013/05/starvation-what-does-it-do-to-the-brain/)
[4] [https://dieteticallyspeaking.com](https://dieteticallyspeaking.com/the-minnesota-starvation-experiment/)